Experimental setups for behavioral analyses.

<p>A) Morphology of Degu hands. Degus have thumb-like structure (top) that allow them to manipulate tools in a dexterous fashion (bottom). B) The homecage of the degus. The degus lived in an “enriched environment” that contained a running wheel, a den, and a tunnel. C) Different levels of tool-use training processes. At Level 1, the degus simply pulled the tools (arrow) toward themselves. At Level 2, the degus had to make lateral movements (arrow*) before pulling the tool toward themselves (arrow**). At Level 2b, the degus had to place the tool beyond the reward before pulling. The degu has grabbed the tool and is about to make a lateral movement and pull the food (down). D) The experimental platform (middle), the TFT monitor for event display (left), and the numeric pad for recording (right). The scale bar is inserted as a rough reference because the photograph is tilted. The degus were placed behind the transparent fence and the experimenter sat facing them from outside of the enclosure. E) A schematic of the radial maze apparatus and the spatial cues. F) A photograph of the radial maze set-up. The experimental platform (middle), the PC for event display (right), and the spatial cues (yellow star, red square and green apple) are visible.